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the main population was male with ages between 16-45 years (Rodríguez-Trigo et al. 2007). 
Maybe this background could explain the higher frequencies of back pain complaints of the 
clean-up workers during the Hebei Spirit clean-up. Interestingly, Na et al. (2012) observed 
also the average duration of the health complaints. The back pain complaints had the lowest 
time of duration, maybe due to the adaption of the physical strain. 
The light blue bars in Figure 7.1 illustrate health symptoms during the Hebei clean-up after 
12 months, which lasted over a year (adopted from Na, et al. 2012). The symptoms and 
health complaints still exist, but the frequencies are decreased. After twelve months continu 
ous clean-up work, headache and eye irritation dominate the health effects among the clean 
up workers. 
For both oil spills, initial phase data on health complaints of the oil spill clean-up workers ex 
ist, when exposure to volatile compounds is expected to be very high. However, uncertainties 
and data gaps limit the informative value: There is no detailed characterization of the clean 
up workers, no data on the work duration, no data on the use and the quality of personal pro 
tective equipment - and no control groups were included in the studies. 
The Prestige oil spill was the only case for which long-term endpoints like genotoxicity were 
investigated (Hildur et al. 2015; Laffon et al. 2014; Monyarch et al. 2013; Perez-Cadahia et 
al. 2008; Rodriguez-Trigo et al. 2010, and data from Gestal-Otero et al., 2004 cited in Rodri- 
guez-Trigo et al., 2007). Furthermore, respiratory effects and oxidative stress markers in the 
lung (Rodriguez-Trigo et al. 2010; Zock et al. 2007; Zock et al. 2014; Zock et al. 2012), as 
well as the impact on psychic health (Carrasco et al. 2007; Sabucedo et al. 2010) were stud 
ied. Respiratory symptoms of the lower respiratory tract were observed up to 5 years after 
the spill. After two years, oxidative stress marker and growth factors were detected in ex 
haled breath condensate. This could be an evidence for lung damage, but also an evidence 
for related repair mechanism. Although the long-term studies are of value, a number of un 
certainties and data gaps limit their explanatory power. 
Genotoxicity was assessed by different methods: the detection of DNA damage described by 
the Comet-Assay and chromosomal alterations described by Micronucleus-Assay, Sister- 
Chromatid-Exchange or karyotyping. In the first year DNA damage was observed in oil spill 
workers with differences regarding their activity, whereby DNA-damage of volunteers corre 
lates with exposure toward VOCs (data from Gestal-Otero et al., 2004 cited in Rodriguez- 
Trigo et al., 2007). Chromosome alterations were observed two and six years after the oil 
spill (Monyarch et al. 2013). However, after six years Hildur et al. (2015) also reported a 
higher prevalence of chromosomal lesions not only in former clean-up workers but also in a 
non-exposed group of fishermen with no participation in clean-up activities in the past com 
pared to a control group located 600 km away from the Prestige accident. The authors dis 
cussed the possibility of indirect exposure of fishermen to some compounds of oil or other 
toxic agents due to the improper storage of the oil or frequently ingestion of low-level con 
taminated sea food. 
Without exposure data from the time of the clean-up activites or current biomonitoring data it 
is difficult to clearly link the described genotoxic effects with the exposure during the clean-up 
activities. 
For exposure-response relationships, the measurements of the personal exposure or bio 
monitoring are important factors. Gestal-Otero (2004) measured the personal VOC exposure 
of different clean-up worker groups. The VOC levels were comparable to highly polluted cit 
ies like Athens or Mexico City with a predominance of light hydrocarbons. Only for benzene 
very high levels were detected. The levels from volunteers (388 pg/rn 3 ) were threefold higher 
than the levels from paid workers (155 pg/rn 3 ) (Rodriguez-Trigo et al., 2007). The high ben 
zene levels of the volunteers correlated with a higher degree of DNA damage.